Autonomous Smart Contract

Massa smart contracts have the unique feature of being able to autonomously define when they will be active, without external actors. By the end of this page, you will have a basic understanding of:

  • How to use the sendMessage(…) ABI in order to make your smart contracts autonomous

  • Provided autonomous smart contracts examples

Use sendMessage to automate your smart contracts

As we’ve just seen, the core principal enabling the autonomous smart contracts feature, is the ability to emit a special message which has the effect of executing a desired function call at a specified window in time, and (optionally) when other specified conditions are met.

The ABI method sendMessage(…) is the key to emitting such a message, and the provided parameters define its configuration:

  • at: Address of the smart-contract that you want to wakeup(can be yourself)

  • functionName: Function of the smart-contract to call

  • validityStartPeriod and validityStartThread: First slot where your message could be executed

  • validityEndPeriod and validityEndThread: Last slot where you message can be executed

  • maxGas: Maximum amount of gas for the execution of the function referenced in the message

  • rawFee: A fee to gain prority in the async pool

  • coins: Coins that will be passed to the smart contract called in the message

  • data: Parameter of the function called in the message

  • filterAddress: An optional address that you can define if you want your function to be executed in your validity period BUT only after a modification in the data of the address (balance, bytecode, datastore)

  • filterKey: An optional datastore key that will execute the message only if there is changes on this datastore key of the filterAddress


You can find an example of autonomous smart contracts in this ticker example, where sendMessage(…) is used in this function.